In his new book, Catching Fire, Richard Wrangham, Ruth Moore Professor of Biological Anthropology at Harvard University, makes the case that cooking was the definitive evolutionary step that made us humans what we are. Gourmet contributing editor Jocelyn Zuckerman spoke with Wrangham about surviving in the bush on a chimpanzee diet; the health claims of raw foodists; and whether cooking can be blamed for the universal subjugation of women.
Jocelyn Zuckerman: According to your “cooking hypothesis,” you believe that it was cooking food—more than eating meat, more than agriculture, more than the advent of tools—that made us who we are, correct?
Richard Wrangham: Yes. People get rather aerated when one says more than this, more than that, but I think that for many people, the point at which Homo erectus emerged—1.8, 1.9 million years ago—was the most dramatic moment in the course of human evolution. And I think that was caused by cooking. Our ancestors from two and a half million years ago had been eating meat, and there’s no question that meat was very important. Agriculture also had immense impact on the total population size and the size of our communities, but it didn’t seem to have the same sorts of changes in our physiology as cooking.
JZ: Can you talk about the nutritional benefits of cooked food?
RW: The two big benefits boil down to, first of all, that cooking increases the digestibility of the specific nutrients. For example, cooking increases the digestibility of starchy foods. If you eat raw starch, then much of it is resistant, which means that you’re not getting the full benefit from it. If you cook it then you get much more energy out of it. So the first big thing that cooking does, and it’s very predictable, is to increase the proportion of the nutrients, particularly starch, but also protein, that goes through your body and is actually digested, as opposed to being passed out unused.
The second thing is the body does a lot of work to digest food, and we know this, of course, because after a heavy meal you feel sleepy. If you do the research you can see that the blood carries oxygen to the tissues of our intestines and away from our peripheral muscles, so no wonder you feel sleepy and physically unenergetic—because your body is doing work to digest, and the amount of work is quite significant. It can be ten or twenty percent of the total caloric value of the meal. Cooking softens the food. It makes it easier for the body, therefore, to digest, just because it is softer and more easily accessed by liquids, more easily churned up by the muscles in the stomach and so on.
There are various experiments that I cite in the book that show this dramatically. [In] the one I love, you take the ordinary hard pellets that rats are given in the laboratory, and you change them simply by adding air—that turns them from something like a wheat grain to a puffed wheat. Then you feed two groups of rats either the hard one or the puffed one; you give them exactly the same number of calories; and you monitor their locomotion so that they spend the same amount of energy involved in locomotion. The ordinary theory would predict that they would gain weight at the same rate. But now when you think about the cost of digestion, you think, well, wait a minute, maybe the one eating the puffed pellet would do better, and indeed they do. They gain weight faster and they have 30 percent more body fat by the time they’re adolescents and early adults.
JZ: And there’s also all the time involved, right?
RW: Think about it: Plato said that intelligent animals are the ones that spend very little time eating. And it’s quite clear now from a number of time-and-motion studies that we spend less than an hour a day chewing our food, whereas if we were a great ape of the chimpanzee-gorilla type, which our ancestors were once, we would be spending something between five or six hours a day eating on average. That would completely change the nature of our lives, because in addition to just literally chewing, you’ve got to find the food. But once you cook, then the food is soft, you can chew it quickly; it radically changes how you spend your time. The irony is, if you look at hunters and gatherers, who are the great evolutionary model for us, women pretty much translate the time gained by cooking into preparing and cooking food. So they appear not to have gained very much. But the men have been freed. Because in all hunter-gatherer societies, just like in every society around the earth, except nowadays some families in modern industrial society, women cook for men.
JZ: That’s a particularly provocative part of the book—where you draw a straight line from the advent of cooking to the subjugation of women.
RW: Yes. I mean, a straight line is a dangerous thing to say, but we do see these very strong influences.
JZ: Why do you think people like Charles Darwin and Claude Lévi-Strauss paid so little attention to cooking?
RW: I think one of the [reasons] is that people found it difficult to think that something as cultural as cooking had really been incorporated into our biology. People always thought about biology as something that did not involve anything as complex as cooking. And there were just no hints, or people never followed up on any hints, that humans are biologically adapted to cooked food. We know that we can eat all sorts of foods raw. And probably people just assumed that humans were like other animals and could eat their food raw and survive on it. For me, it was following chimpanzees, and trying to eat all their food, and sometimes going without any human food all day: I saw that you couldn’t survive on it.
JZ: And it consisted of what, exactly? Berries and leaves?
RW: Something like two thirds of their diet, by the time spent eating, is fruits. But the fruits are not oranges and apples and kiwis and strawberries. They’re like crab apples or something. They’re very dry, and they taste, well, the kind way to put it is “strong,” but basically nasty. You can’t get many of them, and they don’t have anything like the amount of sugar that domesticated varieties do. We’re used to eating fruits that have been the result of several thousands of years of agricultural selection. And if you go out into the wild and start trying to fill your stomach with fruits from wild shrubs and wild trees, you’ll find it very difficult.
JZ: They tasted terrible and you were hungry all the time?
RW: Yes, absolutely. I wouldn’t have survived unless I came back every night and had delicious bowls of steaming pasta.
JZ: So you don’t give much credence to the health claims of present-day raw foodists?
RW: I give a lot of credence to some of the health claims of raw foodists. The fact that I don’t think raw diets are natural does not undermine their claims that they get various kinds of benefits. One benefit of course is [raw foodists] lose weight. Another benefit is that [the diet] reduces various kinds of allergies. I can well believe that some people are sensitive to some of the compounds produced by cooking. I don’t think everybody is.
JZ: Can you talk about how cooking influenced our socialization patterns?
RW: It’s very speculative, but it’s so striking that everybody feels delightfully comfortable around a fire, and once you have fires and meals around a fire, it draws people together in a way that, as somebody who watches chimpanzees, is strikingly different. In general, in animals, where you have individuals living in close proximity on a regular basis, they find ways of solving various social problems, and this can be built into their evolution. Humans as a species, compared to chimpanzees, our closest relatives, are extraordinarily tolerant. We can look into each other’s eyes and chat to each other. We don’t lose our tempers very easily with each other, compared to chimpanzees. This looks like a species that has been through selection for tolerance. We’re clearly just a very nice species in many ways, in terms of our social manners. And so it’s easy to imagine that this, to some extent, happened as a consequence of the importance of being able to gather around a fire and share meals without fighting over them.